1. Field of the Invention
This invention relates to vibrating machine suspensions of the type that isolate machine vibrations from supports.
2. Description of the Prior Art
The present inventor was the co-inventor of U.S. Pat. application Ser. No. 796,623, filed May 13, 1977, and that application has been assigned to the same assignee as the present application. The prior application discloses a vibratory machine of the type having a base, a working member resiliently mounted on the base, and a drive member connected between the base and the working member. The base is isolated from a support structure by means of elastomeric blocks that are positioned on each side of the vibrating machine. The blocks are inclined laterally with respect to the horizontal and have axes perpendicular to their support surfaces which converge about the center of gravity of the vibrating machine. While such elastomeric blocks isolate a substantial amount of the machine vibrations, some vibrations are transmitted to the supports in a direction longitudinally of the vibrating machine. Such vibrations present problems for supports if the frequency of the vibrations is close to the natural frequency of the supports.
U.S. Pat. No. 3,029,924 of Musschoot, which issued on Apr. 17, 1962, shows a stirrup-like structure supporting a vibratory feeder. An instantaneous center of rotation C is located at a point offset from the pivotal axis 26. Superimposed on the oscillatory movement about the center of rotation C is a translatory movement of the feeder due to a periodic component of force acting on a line that passes from the center of percussion, through the center of gravity and the instantaneous center of rotation. The net effect of the forces applied to the feeder by its exciter is to drive the feeder surface so that any given point thereon follows an elliptical path located in a vertical plane.
U.S. Pat. No. 3,347,352 of Gwinn, which issued on Oct. 17, 1967, discloses a vibratory feeder wherein use is made of the feeder inertia for isolating vibration. A feeder base is supported on a supporting structure by rollers that are arranged between inclined surfaces on the supporting structure and complementary inclined surfaces on the base. The surfaces are in parallel plane relationship with each other, and these surfaces support the base for rotation about the center of rotation on one side of the center of gravity of the feeder. When the feeder is so supported, its center of percussion is on the opposite side of the center of gravity. The center of rotation is chosen so that the lines of action, where vibration of the feeder pass through the feeder base portion, are in the region of the center of percussion. When the vibrations pass through the center of percussion, there is not tangential reaction transmitted to the support structure.